Background and Aims: Paravertebral and interpleural blocks are indicated for providing intraoperative and postoperative analgesia in unilateral surgeries of the chest and abdomen. The aim of this study was to evaluate the intraoperative analgesic requirement, efficacy and duration of postoperative analgesia, complications, if any and the time to discharge of patients receiving paravertebral block or interpleural block as an adjuvant to general anaesthesia in patients undergoing breast surgery. Methods: Sixty patients scheduled for breast surgery were randomly allocated into three groups after induction of general anaesthesia: Control group (Group C), paravertebral block group (Group PVB) and interpleural block group (Group IPB). The block was given with 20 ml of 0.5% bupivacaine and 2 µg/kg of clonidine. Results: Sixty five percent patients required intraoperative fentanyl supplements in group C while only 15% patients in group PVB and 35% patients in group IPB required intraoperative fentanyl supplements [P(C/PVB/IPB) <0.01, P(PVB/IPB) = 0.14]. Patients of PVB group had the longest time to first rescue analgesic requirement (13.8 hrs) followed by IPB group (9.6 hrs) and Control group (6.5 hrs). The mean VAS score at rest as well as on movement was significantly lower in PVB group and IPB group compared to Control group. None of the other complications were noted. Conclusion: The use of paravertebral block or interpleural block with bupivacaine and clonidine is a safe and effective technique to enhances the intraoperative and postoperative analgesia, in patients undergoing breast surgery, although the duration of analgesia provided by paravertebral block is more than interpleural block.